1. Field of the Invention
The present invention relates generally to water purification and filtration.
2. Description of the Related Art
A common issue in open ponds, water tanks, and, more specifically, decorative ponds with fish, is preventing and/or controlling the growth of algae, especially floating algae, in the water. Fish produce waste which is composed of mostly ammonia and some solids. Natural bacteria converts the ammonia to nitrite and, in turn, to nitrate. Nitrates then fertilize the water, causing rapid growth of plants and various types of algae. Ammonia and nitrites are toxic to fish, so those levels are monitored in decorative ponds and tanks with fish, and various mechanical filters and/or biological mediums are used to filter out solid waste and to accelerate the natural conversion of nitrites to nitrates. These filters and/or mediums ensure that fish are not harmed by high levels of ammonia and/or nitrites. However, the resultant excess nitrates often cause algae growth to get out of hand, causing the water to appear green and surface algae to cover large portions of the water surface, giving the surface a green slimy appearance. Prevention and/or removal of algae from ponds and tanks is desirable for improved aesthetics.
Several remedies have been used in the past to filter water and/or try to control algae growth. One such remedy is the use of activated charcoal for filtering. Activated charcoal, sometimes referred to as activated carbon or activated coal, is charcoal heated in the presence of a gas, causing it to develop many internal spaces or pores. These small, low-volume pores largely increase the surface area of the activated charcoal for adsorption or chemical reactions.
Adsorption is the adhesion of atoms, ions, or molecules from a gas, liquid, or dissolved solid to a surface, while absorption is adhesion utilizing the whole volume of a material, adsorption is a surface-based process. The extremely porous activated charcoal can act as an adsorbent for contaminants in water, and the pores provide housings for microorganisms to convert ammonia to nitrites and nitrites to nitrates.
However, there is a misconception that activated charcoal removes ammonia, nitrites, and/or nitrates from water on its own. Although activated charcoal is effective in removing certain contaminants, including organics, it is not effective for removal of microbial contaminants, metals, nitrates, and other inorganic contaminants. So, while activated charcoal removes dissolved organic contaminants and impurities from water, the presence of activated charcoal alone can increase the conversion of ammonia and nitrites to nitrates, which ultimately contributes to increased algal growth.
Barley straw has previously been used for algae control. Natural bacteria found in water initiate the breakdown, or biodegradation, of barley straw. During biodegradation of barley straw, natural chemicals are released which inhibit algae growth. As the barley straw degrades, microbes cause the production of humic substances, which in this case are made up of Dissolved Organic Carbon (DOC). Humic acid interacts with sunlight and dissolved oxygen, becomes unstable, and decomposes into oxygen radicals. The oxygen radicals ultimately form low levels of hydrogen peroxide in the water. Hydrogen peroxide, even at low levels, has been shown to inhibit the growth of algae. However, hydrogen peroxide is highly unstable and high levels of it can harm fish and other life, so directly adding hydrogen peroxide to water would be ineffective and counterproductive. Instead, barley straw provides a continuous supply of DOC, which, in turn, produces a steady low supply of hydrogen peroxide to the pond or tank. This continuous supply of low levels of hydrogen peroxide can inhibit or reduce algae growth.
However, barley straw is somewhat difficult to use on its own because it is not a good filter medium, and it can become a nuisance when spread over the water. Also, when placed in water in bales or bundles, barley straw tends to decay into a form which is unattractive and clogs filtration systems.
Activated charcoal and barley straw each provide beneficial effects for filtering open pond and tank water to make it appear clearer. The present invention provides a system and method for utilizing the beneficial effects of both activated charcoal and barley straw.